hydrophila CECT5734. Interestingly, the antimicrobial activity of the respective supernatants was sensitive to proteinase K treatment, but was not affected by the heat treatment, revealing the proteinaceous nature and heat stability of the secreted antimicrobial compounds (i.e., heat-stable bacteriocins). The 24 LAB strains secreting bacteriocins selleck chemical into the liquid growth medium belong
to the species P. pentosaceus (15 strains), E. faecium (8 strains), and Lb. curvatus (1 strain). Table 3 Extracellular antimicrobial activity of the 49 pre-selected LAB a LAB speciesb Strain Indicator microorganisms P. damnosus CECT4797 L. garvieae JIP29-99 A. hydrophila CECT5734 S CS S CS S CS Enterococci E. faecium BNM58 22.4 26.8 14.0 15.0 – - SMA7 – - – - – - SMA8 19.0 19.6 9.4 10.2 – - SMF8 19.0 21.8 10.3 10.8 – - LPP29 20.5 24.4 12.6 13.1 – - CV1 15.0 19.2 – - – - CV2 19.8 23.7 12.7 11.4 – - TPM76 17.0 21.2 – 8.7 – - TPP2 19.7 23.5 12.8 12.4 – - Non-enterococci Lb. curvatus BCS35 18.2 AZD5582 molecular weight 24.7 – - – - P. pentosaceus SMF120 – - – - – - SMF130 7.4 9.7 – - – - SMM73 – 9.5 – - – - BCS46 – 9.4 – - – - B5
8.1 9.0 – - – - B11 – 9.0 – - – - B41 7.3 11.7 – - – - B260 7.3 10.6 – - – - P63 – 9.8 – - – - P621 – 10.5 – - – - LPM78 – 8.3 – - – - LPM83 7.9 11.0 – - – - LPP32 8.5 11.3 – 8.9 – - LPV46 8.2 11.3 – 8.2 – - LPV57 7.6 10.5 – - – - TPP3 9.0 11.7 7.5 9.2 – - aAntimicrobial activity (mm) of supernatants (S) and 20-fold concentrated supernatants (CS) as determined by an ADT. b Lb. carnosus, L. cremoris, Lc. cremoris and W. cibaria
strains did not show extracellular antimicrobial activity against any of the tested indicator microorganisms. In vitro safety assessment of the 49 pre-selected LAB The 49 pre-selected LAB were further submitted to a comprehensive safety assessment by different in vitro tests. Hemolysin production, bile salts deconjugation and mucin degradation MRIP None of the non-enterococcal strains showed hemolytic activity, similarly as found for the 9 enterococci. Moreover, bile salts deconjugation and mucin degradation abilities were not found in any of the tested strains. Enzymatic activities The results of the analysis of enzymatic activity profiles of the tested LAB are shown in Table 4. None of the strains showed lipolytic activity, except E. faecium LPP29, TPM76, SMA7, and SMF8 which produced esterase (C4) and esterase lipase (C8). Moreover, none of the LAB strains showed protease activity (trypsin and α-chymotrypsin). Nevertheless, find more peptidase activity (leucine, valine or cystine arylamidase) was found in all the species. All strains showed acid phosphatase (except E. faecium TPM76 and Lc. cremoris) and naphthol-AS-BI-phosphohydrolase activities, but none displayed alkaline phosphatase activity. β-Galactosidase was found in most species (but not in all strains) except Lb. curvatus and L. cremoris.